Method for manufacturing oxygen sensor

Abstract

The invention provides a method for manufacturing an oxygen sensor that is excellent in responsiveness and can be preferably used for diagnosis of catalyst deterioration. An oxygen sensor 1 equipped with an oxygen sensor element 11 comprising a solid electrolyte 21 and Pt coatings, as a pair of electrodes, on both surfaces of the solid electrolyte 21 is manufactured. The method comprises at least steps of: providing a Pt coating 23 on at least one of the solid electrolyte 21 surfaces exposed to the gas to be tested so as to form closed pores 23 a inside the Pt coating 23 ; and heating either the Pt coating 23 or 24 exposed to gas to be tested in a gas atmosphere with higher oxygen concentration than that of the atmospheric gas.

The invention claimed is: 
     
       1. A method for manufacturing an oxygen sensor equipped with an oxygen sensor element comprising a solid electrolyte and Pt coatings, as a pair of electrodes, on both surfaces thereof,
 the method comprising at least steps of: 
 providing a Pt coating on at least one of the solid electrolyte surfaces exposed to the gas to be tested so as to form closed pores inside the Pt coating; and 
 heating the Pt coating provided on at least the surface exposed to the gas to be tested in a gas atmosphere with higher oxygen concentration than that of the atmospheric gas, and 
 wherein the step of coating is carried out via non-electrolytic platinum plating, and the closed pores are provided inside the Pt coating by bubbling non-oxidizing gas through a plating solution when conducting non-electrolytic platinum plating. 
 
     
     
       2. The method for manufacturing an oxygen sensor according to  claim 1 , wherein the step of heating is carried out at 1,000 degrees C. to 1,300 degrees C. for at least 1 hour.